nRF5x: Refactor gpio_nrf5.c to use the MDK headers #2353
Description
Reported by Carles Cufi:
The nRF5x GPIO implementation redefines some of the structures and macros already present in the MDK in ext/hal/nordic/mdk.
Remove those and use the ones in the MDK instead.
(Imported from Jira ZEP-846)